Journal of Ophthalmic & Vision Research (Jan 2013)
Impression Cytology in Eyes with Clinical and Confocal Scan Features of Acanthamoeba Keratitis
Abstract
Purpose: To report impression cytology findings in specimens obtained from eyes with clinical and confocal microscopic features of Acanthamoeba keratitis (AK). Methods: In this interventional case series, impression cytology was obtained from corneas of patients with clinical and confocal microscopic features indicative of AK. Specimens were stained with Periodic acid-Schiff/Papanicolaou (PAS/PAP) and examined for the presence of PAS-reactive Acanthamoeba cysts and/or hyperchromatic pear-shaped trophozoites. All specimens were then decolorized and re-stained with calcofluor white (CFW) for the presence of chemofluorescent cysts. Results: Fifty-six eyes of 50 patients with mean age of 25.5±9.3 (range, 17 to 78) years were evaluated. Forty-one (82%) cases were female and 51 (91.1%) eyes had history of contact lens wear. PAS-reactive Acanthamoeba cysts and/or hyperchromatic pear-shaped trophozoites were identified in 53 eyes (94.6%), 2 of which demonstrated only trophozoitelike structures. CFW staining was able to reveal the presence of chemofluorescent cysts in all 51 specimens (91.1%) in which cysts had been demonstrated with PAS/PAP staining. Trophozoites were not detected with CFW due to background staining of the cellulose acetate strip used for impression cytology. Conclusion: Corneal impression cytology, stained with PAS/PAP or with CFW, successfully detects Acanthamoeba and can be employed for early noninvasive diagnosis of AK.
